BackgroundInhalation of crystalline silica (cSiO2) is associated with rheumatoid arthritis (RA). Research on cSiO2 has historically focused on professional exposures and on male workers. However, cSiO2 is ubiquitously present in the environment, substantial exposure can take place in both men and women, in other professional activities and even beyond occupational context.ObjectivesTo identify the main sources of exposure to crystalline silica in a series of RA patients not selected based on

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... ir professional activity, and to assess the association between silica exposure and disease features.MethodsThe Dust Exposure Life-Course Questionnaire (DELCQ) is a novel tool that longitudinally quantifies both occupational and non-occupational lifetime exposure to crystalline silica. The DELCQ was previously validated in a representative sample of the general French population that serves as control source for studies in specific diseases. The DELCQ was administered to 97 consecutive patients with RA, exposure scores were compared between cases and age-, sex- and smoking status-matched controls (1:4). The main sources of silica exposure were identified in cases and controls and source-specific exposure levels compared. The association between DELCQ scores and disease variables in cases was tested at uni- and multivariable analysis.ResultsIn women with RA, the main sources of crystalline silica exposure were: cleaning activities, dusty clothes laundry and talcum powder handling, with higher exposure levels from these sources vs. the general population (p<0.005). In the whole series of RA patients, high silica exposure was independently associated with interstitial lung disease (OR 6.5 (95% CI: 1.3 to 32.6)) and mediastinal lymphadenopathy (OR 6.3 (95% CI: 1.4 to 27.7).ConclusionCleaning activities, dusty clothes laundry and talcum handling are underestimated sources of crystalline silica exposure that are overrepresented in women with RA compared to the general population and may contribute to the pathogenesis of the disease.Table 1.Association between occupational silica exposure (by quartile) and HRCT lung abnormalitiesHRCT abnormalityOES(Quartiles)UnadjustedOR (95% CI)AdjustedOR (95% CI)Mediastinal lymphadenopathyQ1-Q3(ref)(ref)Q44.1 (1.2 to 13.9)6.3 (1.4 to 27.7)Interstitial lung diseaseQ1-Q3(ref)(ref)Q46.3 (1.5 to 26.6)6.5 (1.3 to 32.6)EmphysemaQ1-Q3(ref)(ref)Q46.4 (1.6 to 24.7)2.9 (0.6 to 13.7)Abbreviations: OES occupational exposure score. Adjusted OR: adjusted on smoking, sex, disease duration, ACPA and RF status.Disclosure of InterestsNone declared.